I. Long-term variations of periods and amplitudes
Instytut Astronomiczny Uniwersytetu Wrocławskiego, Kopernika 11, 51-622 Wrocław, Poland e-mail: email@example.com
2 Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Al. Ujazdowskie 4, 00-478 Warszawa, Poland e-mail: firstname.lastname@example.org
Accepted: 7 November 2007
Aims.We analyse V-filter ASAS-3 photometry of 41 known β Cephei-type stars. The ASAS-3 photometry is combined with the archival data, if available, to determine long-term stability of periods and amplitudes of excited modes.
Methods.Frequencies of modes are derived by means of Fourier periodograms with consecutive prewhitening. The results are examined in the context of detection threshold.
Results.We detected amplitude changes in three β Cephei stars, BW Cru, V836 Cen, and V348 Nor. Period changes were found in KK Vel and V836 Cen. Our analysis shows that intrinsic period changes are more common among multiperiodic stars, apparently because they are caused by some kind of mode interaction. In addition, we found new modes for seven stars, and for ten others we provide new solutions or remove ambiguities in the detected frequencies. One candidate hybrid β Cephei/SPB star, HD 133823, is discovered.
Key words: stars: early-type / stars: oscillations / surveys
Appendix A, Figs. 2–6 and Tables 2–6 are only available in electronic form at http://www.aanda.org
© ESO, 2008